Chocolate is a food with high fat and high energy content, with a total fat content (including emulsifiers) of up to 45% by weight. A typical milk chocolate for example may contain 31% fat, 7% protein and 56% carbohydrate with an energy value of 531 kcal/100 g. Fat provides about 53% of this energy. Internationally accepted nutritional guidelines propose that fat should provide no more than 30% to 35% energy. In countries where overweight and obesity are common, the total energy content of the diet should be reduced. There are thus cogent arguments for reducing both the fat and energy contents of chocolate.
In theory, reduction in the fat content of chocolate can be simply achieved by reducing the amount of fat ingredients; such as cocoa butter or milk fat, or of fat-containing ingredients; such as cocoa liquor, milk powder or hazelnut. There are however legal and technical restraints on fat reduction in chocolate. Legally, chocolate needs to contain a minimum of 25% fat. Although this limit would not apply to "imitation chocolate", it is a barrier to fat and calorie reduction in true chocolate. For example, a reduction from 31% to 25% fat with replacement by carbohydrate would give an energy reduction of only 30 kcal/100 g. Technical problems arise owing to the increase of viscosity of the chocolate mass as the fat content is reduced. This leads to conching of chocolate being more difficult and less effective, resulting in less flavour development. Additionally the reduction in fat available to coat the ingredients, notably sugar, leads to chocolate of inferior mouthfeel.
A radical solution to the issue of fat content in chocolate is the substitution of cocoa butter by partially or wholly non-metabolisable fats. This is disclosed, for example, in EP-A-0285187, EP-A-0285187 and EP-A-0495553. There are two major disadvantages in using non-metabolisable fats in chocolate; the formulations do not conform to legal standards for chocolate and these "fats" may cause anal leakage, of which the latter effect is likely to limit acceptability by consumers.
Concerning the more general proposition of reducing the calorie content of chocolate, the most successful approach involves replacement of sucrose by partially metabolisable carbohydrates. There are many specific disclosures including EP-A-0317917 and EP-A-0512910 involving this approach. Sugar replacers fall into two categories, polyols and bulking agents. Polyols, sometimes called sugar alcohols, are essentially hydrogenated sugars exemplified by sorbitol, isomalt, maltitol, lactitol, erythritol and xylitol, amongst others. Bulking agents consist of polymers of readily metabolised sugars like glucose and fructose linked by bonds which cannot be split by the enzymes of the digestive system. Examples of bulking agents are polydextrose, oligofructose and inulin. Both polyols and bulking agents are partially metabolised by intestinal flora and so provide some energy. Most polvols are accorded an energy value of 2.4 kcal/g, polydextrose 1.0 kcal/g, and the energy value of other bulking agents has yet to be agreed. These energy figures compare with 4 kcal/g for sucrose, so that when 45 g sucrose is replaced by polyol, the energy reduction in chocolate is 72 kcal/100 g, whilst when such an amount of sucrose is replaced by 22.5 g each of polyol and polydextrose, the energy reduction is 103.5 kcal/100 g. Technically, both polyols and bulking agents increase the viscosity of the chocolate mass compared with sucrose. Thus, high fat levels in such chocolates need to be maintained in order to decrease viscosity, while the temperature of conching has to be lowered, leading to less effective flavour development. The retention of high fat levels limits calorie reduction and makes unrealistic the 25% to 30% reduction in calories demanded by some regulators to classify a food as "reduced calorie".
Other food ingredients that are not metabolised and which are of zero calorific value (such as dietary fibre, for example cellulose, particularly methyl cellulose, pectins, edible gums, cereal fibres and vegetable fibers), can be introduced into the initial recipe mix in amounts up to about 7.5% by weight, preferably less than 5%. The present invention is also applicable to such mixes.
The need is for a process suitable for regular and low calorie chocolate allowing product to be made with 25% fat or less, yet which allows good flavour development during conching. The present invention does this by making a full fat, full flavour chocolate and then subsequently reducing the fat content.